3D Conductive Network Structure Research Articles

NiS2 @MWCNTs as a promising anode material for lithium and sodium-ion batteries with superior cycling stability

The NiS2 @MWCNTs materials were synthesized using a straightforward hydrothermal one-step process, forming a 3D conductive network structure with stable and uniformly distributed nanosphere morphology. Electrochemical tests yielded a sodium storage capacity of 463.99 mAh g−1 after 400 cycles with 0.2 A g−1, and a coulomb efficiency of 83.3% at the first cycle, followed by excellent long-cycle stability with a capacity retention rate of 96.7% after 600 cycles at a high current of 1 A g−1. It's interesting to note that Na+ storage mechanism is provided by a pseudocapacitor. The 3D conductive network was credited with enhanced electrochemical performance and structural stability. The incorporation of multi-walled carbon nanotubes (MWCNTs) also improves the material conductivity and accelerated the ion transport efficiency, while modulation of the nano microsphere structure increases the reactive active sites and reduce the capacity loss. These findings highlight the great potential NiS2 @MWCNTs composites as a perfect anode material for sodium-ion batteries (SIBs), opening up new possibilities for sustainable energy storage solutions.

Modification of VPO4 with carbon and 3DG for high performance lithium‐ion battery anode

AbstractLithium‐ion batteries (LiBs) are one of the most promising energy storage devices. However, the large‐scale application of LiBs is limited by their electrochemical properties. In this study, we built a three‐dimensional (3D) conductive network structure with carbon and 3DG coating VPO4 (VPO4@C@3DG) via a one‐pot hydrothermal method with subsequent high‐temperature annealing. The effects of the content of three‐dimensional porous graphene (3DG) on the crystal structure, morphology, and electrochemical properties of VPO4/C are investigated using characterization and electrochemical test techniques. The SEM images show that the size of sphere‐like particles of VPO4@C@3DG composite with 20 wt.% of 3DG (VPO4@C@3DG‐20) is the smallest in all samples. In addition, the electrochemical experimental results reveal that VPO4@C@3DG‐20 exhibits the best cycling and rate performance compared to other VPO4@C@3DG composites. Specifically, VPO4@C@3DG‐20 achieves an initial charge capacity of 601.2 mAh g−1 at 0.2 C (110 mA g−1) and keeps at 354 mAh g−1 at the 100th cycle. This is because the introduction of 20 wt.% 3DG graphene inhibits the growth and aggregation of the particles, thus shortening the diffusion path of Li+. In addition, the 3D conducting network structure boosts the conductivity of the materials and buffers the volume variation resulting from the charging/discharging process.

In situ synthesis of VS4/Ti3C2Tx MXene composites as modified separators for lithium-sulfur battery

Lithium-sulfur (Li-S) batteries are regarded as highly prospective energy storage devices. However, problems such as low sulfur utilization, poor cycle performance, and insufficient rate capability hinder the commercial development of Li-S batteries. Three-dimensional (3D) structure materials have been applied to modify the separator of Li-S batteries to suppress the diffusion of lithium polysulfides (LiPSs) and inhibit the transmembrane diffusion of Li+. A vanadium sulfide/titanium carbide (VS4/Ti3C2Tx) MXene composite with a 3D conductive network structure has been synthesized in situ by a simple hydrothermal reaction. VS4 is uniformly loaded on the Ti3C2Tx nanosheets through vanadium-carbon(V-C) bonds, which effectively inhibits the self-stacking of Ti3C2Tx. The synergistic action of VS4 and Ti3C2Tx substantially reduces the shuttle of LiPSs, improves interfacial charge transfer, and boosts the kinetics of LiPSs conversion, consequently increasing the rate performance and cycle stability of the battery. The assembled battery has a specific discharge capacity of 657 mAhg-1 after 500 cycles at 1C, with a high capacity retention rate of 71%. The construction of VS4/Ti3C2Tx composite with a 3D conductive network structure provides a feasible strategy for the application of polar semiconductor materials in Li-S batteries. It also provides an effective solution for the design of high-performance Li-S batteries.

A water-based binder with 3D network enabling long-cycle-life silicon/graphite composite anode materials for lithium ion batteries

A binder with strong bonding and 3D network is proven to be beneficial for the electrochemical performance of silicon anode material. Herein, a water-soluble binder with strong adhesion and 3D conductive structure is prepared by a one-pot method. The polymer consists of acrylic acid (AA), acrylamide (AM), and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) forming a terpolymer (PtA), which is grafted to polyvinyl alcohol (PVA) chains to construct a strong hydrogen bonding 3D conductive network structure (PtA/PVA). The polar groups (-COOH and -CONH2) provide strong hydrogen bonding and intermolecular forces for adhesion, while the introduction of lithium salts and sulfonic acid groups provides fast channels for ion transport. In addition, the PVA links with abundant hydroxyl groups, conferring excellent electrochemical performance of silicon/graphite (Si@C 400) composite anodes. As a result, the Si@C 400 anode with the PtA/PVA binder has a reversible capacity of up to 329.8 mAh g−1 at 0.1C, and it shows a prolonged cycle life of 82.0% after 500 cycles at 0.5C. This study provides a promising strategy to design binder for silicon anodes with enhanced electrochemical properties.

Controllable Preparation of Ge/Cu Composite Porous Microspheres as High‐Performance Anode Materials for Lithium‐Ion Batteries

Germanium (Ge) has great advantages as a cathode material for lithium‐ion batteries, but its application in the anode of lithium‐ion batteries is limited by its volume expansion and poor electrical conductivity. Currently, nano‐Ge and composite Ge are the main research directions. Using Ge/copper (Cu) alloy as raw material, herein, pulse discharge and chemical etching method are adopted to prepare a kind of Ge/Cu composite porous microsphere (Ge/Cu@PMS). A 3D conductive network structure is obtained to increase the conductivity of Ge and alleviate the volume expansion of lithium‐ion battery during charge and discharge. As an anode material for Li‐ion batteries, Ge/Cu@PMS has a capacity retention rate reaching 590 mAh g−1 after 200 constant current charge–discharge cycles at a current density of 800 mA g−1, with a capacity retention rate of 79.1%. Therefore, Ge/Cu@PMS has great potential application in lithium energy storage‐related technologies due to its excellent energy‐storage performance and ease of preparation.

3D C-Co-N-anchored MWCNTs derived from metal-organic frameworks as high-performance electrochemical sensing platforms for the sensitive detection of adrenaline.

Metal-organic frameworks (MOFs) are composed of metal ions and organic ligands with high specific surface areas, controllable porous structures and abundant metal active sites, showing their extraordinary potential in electrochemical sensors. Here, a 3D conductive network structure (C-Co-N@MWCNTs) is designed by anchoring zeolite imidazole frameworks (ZIF-67) onto multi-walled carbon nanotubes (MWCNTs) and carbonizing them. The C-Co-N@MWCNTs exhibit excellent electron conductivity, a porous structure and considerable electrochemical active sites, which can effectively demonstrate high sensitivity and selectivity in the detection of adrenaline (Ad). The Ad sensor exhibited a low detection limit of 6.7 nmol L-1 (S/N = 3) and a wide linear range of 0.02 μmol L-1-1.0 mmol L-1. The developed sensor also displayed high selectivity, good reproducibility and repeatability. The C-Co-N@MWCNTs electrode was further employed in the detection of Ad in a real sample of human serum, suggesting that it is a promising candidate for electrochemical sensing of Ad.

A carbon-covered silicon material modified by phytic acid with 3D conductive network as anode for lithium-ion batteries

The requirement for silicon-based anode material is growing and has received attentions. Silicon is a promising anode material for lithium-ion batteries due to the high theoretical capacity. However, the high volumetric variability of silicon has led to severe chalking and rapid capacity degradation. To ameliorate these problems, a carbon-covered silicon material with a 3D conductive network structure was prepared employing glucose and phytic acid as carbon sources. When acted as the anode for Lithium-ion batteries, the prepared composite material delivered 1612 mAh/g in the first cycle and approximately 600 mAh/g at 0.1 A/g after 200 cycles. In addition, even at 5 A/g, a high capacity of 503 mAh/g was reached, and when recovered to 0.1 A/g, the capacity of 878 mAh/g was maintained.

Medium-Entropy-Alloy FeCoNi Enables Lithium-Sulfur Batteries with Superb Low-Temperature Performance.

Lithium-sulfur battery suffers from sluggish kinetics at low temperatures, resulting in serious polarization and reduced capacity. Here, this work introduces medium-entropy-alloy FeCoNi as catalysts and carbon nanofibers (CNFs) as hosts. FeCoNi nanoparticles are in suit synthesized in cotton-derived CNFs. FeCoNi with atomic-level mixing of each element can effectively modulate lithium polysulfides (LiPSs), multiple components making them promising to catalyze more LiPSs species. The higher configurational entropy endows FeCoNi@CNFs with extraordinary electrochemical activity, corrosion resistance, and mechanical properties. The fractal structure of CNFs provides a large specific surface area, leaving room for volume expansion and Li2 S accumulation, facilitating electrolyte wetting. The unique 3D conductive network structure can suppress the shuttle effect by physicochemical adsorption of LiPSs. This work systematically evaluates the performance of the obtained Li2 S6 /FeCoNi@CNFs electrode. The initial discharge capacity of Li2 S6 /FeCoNi@CNFs reaches 1670.8 mAh g-1 at 0.1 C under -20°C. After 100 cycles at 0.2 C, the capacity decreases from 1462.3 to 1250.1 mAh g-1 . Notably, even under -40°C at 0.1 C, the initial discharge capacity of Li2 S6 /FeCoNi@CNFs still reaches 1202.8 mAh g-1 . After 100 cycles at 0.2 C, the capacity retention rate is 50%. This work has important implications for the development of low-temperature Li-S batteries.

Rational construction of 2D/2D Ti3C2Tx/NiCo MOF heterostructure for highly efficient Li+ storage

Metal-organic framework (MOFs) have been regarded as ideal lithium-ion battery (LIB) anodes with abundant active sites, porous structure, shortened ion diffusion pathways, and adjustable component, but the MOF anodes suffer from the low electronic conductivity. Herein, we rationally design a 2D/2D Ti3C2Tx/NiCo MOF heterostructure through in-situ growth of ultrathin NiCo MOF nanosheets on the few-layer Ti3C2Tx MXene sheets. The carboxylate groups of BDC2− can form stable bond with the termination groups (e.g., -OH) on the Ti3C2Tx surface and hydroxyl groups in the lignin molecules, resulting in stable Ti3C2Tx/NiCo MOF interface and good structure stability of the 2D/2D Ti3C2Tx/NiCo MOF heterostructure. The Ti3C2Tx/NiCo MOF heterostructure could combine the advantages of 2D MXene nanosheets and 2D bimetallic MOF structure. The 2D bimetallic NiCo MOF can offer plenty of exposed active sites for Li+ intercalation, while the 3D conductive network structure based on the Ti3C2Tx can not only enhance the electronic conductivity, but also facilitate the electrode/electrolyte interface contact and promote the charge diffusion. The obtained 2D/2D Ti3C2Tx/NiCo MOF heterostructure anode demonstrates a high capacity of 637 mAh g−1 at 0.2 A g−1 after 200 cycles. Furthermore, the Li+ intercalation/extraction mechanism of the Ti3C2Tx/NiCo MOF heterostructure electrode is explored in detail.

Waste Silicone Rubber in Three-Dimensional Conductive Networks as a Temperature and Movement Sensor.

Constructing a three-dimensional (3D) conductive network in a polymer matrix is a common method for preparing flexible sensors. However, the previously reported methods for constructing a 3D conductive network generally have shortcomings such as uncontrollable processes and insufficient network continuity, which limit the practical application of this method. In this work, we report a method for constructing a dual 3D conductive network. The carbon nanotube/graphene oxide co-continuous network (primary network) was introduced on the surface of the waste silicone rubber particles (WSRPs) through the adhesion of polydopamine (PDA), and then WSRPs were bonded into a porous skeleton using nanocellulose. The carbon fiber/carbon ball interconnection network (secondary network) was constructed in liquid silicone rubber (LSR) through the interaction of host-guest dendrimers and was filled into the WSRP skeleton. The dual 3D conductive network structure endowed the sensor with high electrical and thermal conductivity, outstanding stability, and excellent durability. In addition, the sensor showed high strain sensitivity and excellent stability when detecting human body temperature and motion behavior, and the pressure distribution can be spatially mapped through the sensor matrix. These demonstrations give our sensor high potential in the fields of smart devices, body monitoring, and human-machine interfaces.

Flexible Porous Silicon/Carbon Fiber Anode for High-Performance Lithium-Ion Batteries.

We demonstrate a cross−linked, 3D conductive network structure, porous silicon@carbon nanofiber (P−Si@CNF) anode by magnesium thermal reduction (MR) and the electrospinning methods. The P−Si thermally reduced from silica (SiO2) preserved the monodisperse spheric morphology which can effectively achieve good dispersion in the carbon matrix. The mesoporous structure of P–Si and internal nanopores can effectively relieve the volume expansion to ensure the structure integrity, and its high specific surface area enhances the multi−position electrical contact with the carbon material to improve the conductivity. Additionally, the electrospun CNFs exhibited 3D conductive frameworks that provide pathways for rapid electron/ion diffusion. Through the structural design, key basic scientific problems such as electron/ion transport and the process of lithiation/delithiation can be solved to enhance the cyclic stability. As expected, the P−Si@CNFs showed a high capacity of 907.3 mAh g−1 after 100 cycles at a current density of 100 mA g−1 and excellent cycling performance, with 625.6 mAh g−1 maintained even after 300 cycles. This work develops an alternative approach to solve the key problem of Si nanoparticles’ uneven dispersion in a carbon matrix.

Incorporation of Fe3O4 nanoparticles in three-dimensional carbon nanofiber/carbon nanotube aerogels for high-performance anodes of lithium-ion batteries

Recently, Fe3O4 based materials have been widely investigated to serve as anode materials of lithium-ion batteries (LIBs) because of the high theoretical capacity (924 mA h g−1). Unfortunately, the actual capacity of these materials are low and they suffer from poor cycling stability. Herein, carbon nanotube/carbon nanofiber composite aerogels (CA) were used as scaffold to fabricate Fe3O4-CA composites for anode materials. Fe3O4 nanoparticles were evenly presented on the external surface and internal channel of the 3-dimensional (3D) CA network. The 3D conductive network can buffer the volume expansion of anode materials. Additionally, such structure can prevent the aggregation of Fe3O4. Therefore, the structure of the Fe3O4-CA composite electrode can be maintained during lithiation/delithiation processes. The Fe3O4-CA composites delivered a high reversible capacity of 825.1 mA h g−1 after 100 cycles. Additionally, an ultra-high coulombic efficiency closed to 100% was obtained. The excellent performance of the Fe3O4-CA composites may be due to the synergistic effect of the Fe3O4 nanoparticles and 3D conductive network structure.

High conductivity and stability of polystyrene/MXene composites with orientation-3D network binary structure

Recently, two-dimensional transition metal carbide/nitride (MXene) and its composites with polymers have attracted great interest from researchers due to their potential applications in flexible electronics, electromagnetic shielding, catalysis, and energy storage. However, the easy oxidation of MXene and the low efficiency of traditional composites preparation methods have brought great challenges to the practical application of polymer/MXene composites. Here, we prepared polystyrene/Mxene (PS/MXene) composites with a 3D conductive network structure through particle construction strategy. Because of the compact and ordered structure, the conductivity of the material reached 3846.15 S/m when the filler content was only 1.81 vol%, and it can retain 53.4% of the initial value after 180 days. Furthermore, based on the 3D network, we orientated the MXene nanosheets in the matrix to form the MXene orientated 3D network binary structure. This unique structure design further increased the utilization rate of MXene and made the material conductivity reach to 4471.13 S/m, with the percolation threshold as low as 0.175 vol%. We believe that this research can provide a feasible way for the practical application of MXene composite materials.

N-self-doped graphitic carbon aerogels derived from metal–organic frameworks as supercapacitor electrode materials with high-performance

Metal–organic frameworks (MOFs) are promising precursors to prepare heteroatom-doped porous carbon for high-performance supercapacitor. N-self-doped graphitic carbon aerogels (NGCA) with hierarchically porous tunnels, high graphitization degree, high N content and 3D conductive network structure are successfully prepared by dry-freezing and successive high temperature treatment of ZIF-8/carboxymethylcellulose (CMC)/potassium ferrate (K2FeO4) composites, using CMC as continuous carbon agent for MOFs-derived carbon and K2FeO4 as both activation agent and catalyst. When applied in a supercapacitor, the obtained NGCA exhibit excellent capacitive performance and remarkable energy-power characteristics. The specific capacitance of NGCA electrode is 244 F/g at 1 A/g in three-electrode system. NGCA based symmetric supercapacitor shows a high energy density of 17.08 Wh/kg at a power density of 500 W/kg. These results confirm NGCA as electrode material can be applied for high-performance supercapacitor.

Binder-Free Two-Dimensional MXene/Acid Activated Carbon for High-Performance Supercapacitors and Methylene Blue Adsorption

In this paper, we have synthesized the two-dimensional (2D) MXene layers and acid activated carbon (AAC) into a 3D conductive network structure, which could prevent the serious aggregation of 2D MX...

Epoxy resin based composite filled with low-loading LRGO@AC and CoFe2O4 for excellent electromagnetic absorption performance

In this work, large-sized reduced graphene oxide@activated carbon (LRGO@AC) and CoFe2O4 were prepared by thermal reduction and solvothermal method. The epoxy resin based composites were successfully synthesized via a simple physical mixing way. Its complex permittivity, permeability, and reflection loss (RL) were characterized by using an Agilent N5234A vector network analyzer. The results showed that the LRGO@AC/CoFe2O4/epoxy composite presented excellent EM wave absorption performance at a 5 wt% loading of LRGO@AC/CoFe2O4. The minimum RL value reached − 42.70 dB at 11.24 GHz and the effective absorption bandwidth (RL < − 10 dB) reached 5.45 GHz with a matching thickness of 3.0 mm. The excellent EM wave absorption performance was due to the unique 3D conductive network structure of LRGO which is conducive to the uniform dispersion of LRGO@AC and CoFe2O4 in the matrix, which facilitates the interaction of the filler in the epoxy resin and promotes the synergistic effect of electromagnetic loss. Moreover, the results of HFSS show that the radar cross section (RCS) can be reduced rapidly. Therefore, the LRGO@AC/CoFe2O4 would be a useful absorbing material.

A 3D conductive network of porous carbon nanoparticles interconnected with carbon nanotubes as the sulfur host for long cycle life lithium–sulfur batteries

Constructing an interlinked three-dimensional conductive carbon structure as a sulfur host is considered to be an effective strategy for suppressing the capacity decay over long-term cycling and improving the rate performance of lithium-sulfur (Li-S) batteries, because it can not only facilitate rapid electronic and ionic transportation in the cathode, but also be conducive to confine lithium polysulfide (LiPS) dissolution and shuttling. In this report, we designed a novel 3D conductive network structure (CNTs/Co-NC), which is composed of Co-NC (cobalt embedded in an N-doped porous carbon composite) derived from ZIF-67 polyhedra and inserted carbon nanotubes (CNTs), and applied it as a sulfur host for Li-S batteries. The CNT/Co-NC network structure is firstly prepared via the in situ nucleation of small ZIF-67 crystals on the surface of CNTs and eventually grown into CNT/ZIF-67 hybrid materials; after subsequent carbonization and infiltration of sulfur procedures, the S@CNT/Co-NC cathode is obtained. Li-S batteries based on the S@CNT/Co-NC cathode show an improved rate capability of 772.6 mA h g-1 at the 2 C rate, enhanced long cycling stability under a large current density with a low capacity decay rate of ∼0.067% per cycle at the 0.5 C rate after 500 cycles and ∼0.072% per cycle at the 1 C rate after 700 cycles and an excellent coulombic efficiency of about 95% up to 500 cycles at 0.5 C and 91% up to 700 cycles at 1 C. The superior performance of S@CNTs/Co-NC should be ascribed to the rapid charge transfer, excellent electron conductivity, improved adsorption capability for LiPSs and enhanced redox kinetics of this 3D conductive network structure.

NiO/CNTs derived from metal-organic frameworks as superior anode material for lithium-ion batteries

In this work, porous NiO microspheres interconnected by carbon nanotubes (NiO/CNTs) were successfully fabricated by the pyrolysis of nickel metal-organic framework precursors with CNTs and evaluated as anode materials for lithium-ion batteries (LIBs). The structures, morphologies, and electrochemical performances of the samples were characterized by X-ray diffraction, N2 adsorption-desorption, field emission scanning electron microscopy, cyclic voltammetry, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy, respectively. The results show that the introduction of CNTs can improve the lithium-ion storage performance of NiO/CNT composites. Especially, NiO/CNTs-10 exhibits the highest reversible capacity of 812 mAh g−1 at 100 mA g−1 after 100 cycles. Even cycled at 2 A g−1, it still maintains a stable capacity of 502 mAh g−1 after 300 cycles. The excellent electrochemical performance of NiO/CNT composites should be attributed to the formation of 3D conductive network structure with porous NiO microspheres linked by CNTs, which benefits the electron transfer ability and the buffering of the volume expansion during the cycling process.

A cylindrical FePO4/MWCNTs composite with a 3D conductive network structure used as a cathode material for lithium-ion batteries

FePO4/MWCNTs (multi-wall carbon nanotubes) composite with a cylindrical core-shell 3D conductive network structure has been fabricated by a simple micro-emulsion technique. Results indicate that FePO4 nanoparticles with a diameter of 10–20 nm are loaded onto the surfaces of MWCNTs, forming a cylindrical core-shell 3D conductive network structure of FePO4/MWCNTs composite. The micro-emulsion plays two key roles in the synthetic process: firstly, dispersing the MWCNTs uniformly, attributing to the presence of an oil phase in the micro-emulsion system; secondly, synthesizing nanoparticle-sized FePO4 due to the nano-sized water nuclear in the micro-emulsion system, decreasing the aggregation of nano-sized FePO4 particles. The FePO4/MWCNTs composite shows excellent electrochemical performance with high discharge capacity, excellent reversibility, and cycling stability.

LiFePO4/C composite with 3D carbon conductive network for rechargeable lithium ion batteries

A novel LiFePO4/C composite with 3D carbon network was prepared using Cetyltrimethyl Ammonium Bromid (CTAB) and starch as carbon sources via a facile method. The 3D carbon network structure was composed of a full and uniform carbon coating and a continuous carbon film framework. Good conductive paths enhancing electrons transfer efficiency and porous structure facilitating diffusion of lithium ions have been constructed by the 3D conductive network structure, which contributes the high ionic and electrical conductivities. As a result, the LiFePO4/C composite possesses an excellent electrochemical performance especially the high-rate cyclic performance. It delivers a capacity of 95mAhg−1 at current density of 3.4Ag−1 (20C). After 1200 cycles, the discharge capacity of 74mAhg−1 can still be obtained, almost reaching a retention of 80%, which is higher than the best cyclic performance in previous investigations.